Liquid crystal monitors for image display are being used not only in offices or households but also at sites of various kinds of professional work, such as graphic design and medical care. In particular, high-end liquid crystal monitors are being used to display graphic design images or medical diagnostic images, since display of such images requires high-definition image quality having high reproducibility. In recent years, of such liquid crystal monitors, models have become commercially available that enhance the reproducibility of display images by measuring an optical property(s) of the liquid crystal screen, such as luminance, chromaticity, or light quantity, using an optical sensor and then performing calibration on the basis of the measurement data obtained.
A liquid crystal monitor includes a liquid crystal display panel, a bezel surrounding the liquid crystal display panel, a backlight, various types of electronic circuits, and the like. Examples of known documents related to a configuration in which calibration is performed include an optical sensor device of an optical measuring device that includes an optical measuring device main body and a sensor unit including an optical sensor used to measure the luminance, chromaticity, or the like of the monitor screen and that moves the sensor unit out of the optical measuring device main body to the measurement position of the target screen (the monitor screen) to make a measurement, and, after the measurement, stores the sensor unit in the optical measuring device main body (Patent Document 1). The optical sensor device of Patent Document 1 includes an optical measuring device main body 204, a single shaft configured to rotatably support a sensor unit 103, a first follower configured to rotate the shaft, a second follower configured to move the shaft back and forth, and a drive transmission mechanism configured to drive these followers. This optical sensor device is attached to a liquid crystal monitor and used (FIG. 31).